The present invention relates to traffic control barriers and, more particularly, to traffic control barriers of the type having an arm which is lowered to provide a barrier and which can be raised to allow traffic to pass past the barrier.
Existing motorised barriers require heavy duty motors in order to raise and lower the arm, despite the counterbalancing of the arm. This is because it is difficult to balance the arm at all positions and, therefore, the residual force on the arm and hence on the motor varies as the arm moves. Thus the motor must be rated sufficiently highly to cope with the maximum gravitational force on the arm that will need to be overcome during its movement.
The present invention sets out to overcome this problem and has the objectives of enabling the use of smaller capacity motors than hitherto, whilst ensuring a smoother arm movement, using simple, reliable components and providing a fail-safe mechanism, to prevent the arm from falling if the mechanism fails and to prevent the arm from being raised if a relatively large load is added to the arm, such as a child swinging on the arm. It is also an objective of the present invention to produce a compact structure.